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<table width="100%" summary="page for ryegrass"><tr><td>ryegrass</td><td style="text-align: right;">R Documentation</td></tr></table>

<h2>Effect of ferulic acid on growth of ryegrass</h2>

<h3>Description</h3>

<p>A single dose-response curve.
</p>


<h3>Usage</h3>

<pre>data(ryegrass)</pre>


<h3>Format</h3>

<p>A data frame with 24 observations on the following 2 variables.
</p>

<dl>
<dt>rootl</dt><dd><p>a numeric vector of root lengths</p>
</dd>  
<dt>conc</dt><dd><p>a numeric vector of concentrations of ferulic acid</p>
</dd>
</dl>



<h3>Details</h3>

<p>The data are part of a study to investigate the joint action
of phenolic acids on root growth inhibition of perennial ryegrass (<em>Lolium perenne L</em>).
</p>
<p><code>conc</code> is the concentration of ferulic acid is in mM, and <code>rootl</code> is the root length 
of perennial ryegrass measured in cm. 
</p>


<h3>Source</h3>

<p>Inderjit and J. C. Streibig, and M. Olofsdotter (2002) Joint action of
phenolic acid mixtures and its significance in allelopathy
research, <em>Physiologia Plantarum</em>, <b>114</b>, 422&ndash;428, 2002.
</p>


<h3>Examples</h3>

<pre>

## Displaying the data set
ryegrass

## Fitting a four-parameter Weibull model (type 2)
ryegrass.m1 &lt;- drm(rootl ~ conc, data = ryegrass, fct = W2.4())

## Displaying a summary of the model fit
summary(ryegrass.m1)

## Plotting the fitted curve together with the original data
plot(ryegrass.m1)

## Fitting a four-parameter Weibull model (type 1)
ryegrass.m2 &lt;- drm(rootl ~ conc, data = ryegrass, fct = W1.4())
plot(ryegrass.m2)

## Fitting a four-parameter log-logistic model
## with user-defined parameter names
ryegrass.m3 &lt;- drm(rootl ~ conc, data = ryegrass, 
fct = LL.4(names = c("Slope", "Lower Limit", "Upper Limit", "ED50")))
summary(ryegrass.m3)

## Comparing log-logistic and Weibull models
## (Figure 2 in Ritz (2009))
ryegrass.m0 &lt;- drm(rootl ~ conc, data = ryegrass, fct = LL.4())
ryegrass.m1 &lt;- drm(rootl ~ conc, data = ryegrass, fct = W1.4())
ryegrass.m2 &lt;- drm(rootl ~ conc, data = ryegrass, fct = W2.4())

plot(ryegrass.m0, broken=TRUE, xlab="Dose (mM)", ylab="Root length (cm)", lwd=2, 
cex=1.2, cex.axis=1.2, cex.lab=1.2)
plot(ryegrass.m1, add=TRUE, broken=TRUE, lty=2, lwd=2)
plot(ryegrass.m2, add=TRUE, broken=TRUE, lty=3, lwd=2)

arrows(3, 7.5, 1.4, 7.5, 0.15, lwd=2)
text(3,7.5, "Weibull-2", pos=4, cex=1.2)

arrows(2.5, 0.9, 5.7, 0.9, 0.15, lwd=2)
text(3,0.9, "Weibull-1", pos=2, cex=1.2)


</pre>


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